Method for forming the vacuumtight closure of a through-connection

ABSTRACT

A method of hermetically sealing a wire, such as a lead-in conductor for an electrical device, in a metal tube in which the wire is passed through the tube, a portion of the tube constricted about the wire, and forcing the wire into one end of the tube which causes the tube to bulge out and the wire thickened beyond the initial diameter of the tube.

United States Patent Bottcher 1 Feb. 1, 1972 [54] METHOD FOR FORMING THE [56] References Cited VACUUMTIGHT CLOSURE OF A THROUGH CONNECTION UNITED STATES PATENTS Inventor: Karhfleinz Bottcher, Munich schwab 12/ lligzger ..219/ 152 Germany 2,896,981 7/1959 Cooney.. [73] Assignee: U.S. Philips Corporation, New York, NY. 2,958,759 11/1960 Snell ..219/152 [221 May FOREIGN PATENTS OR APPLlCATlONS APPL 37138 40,684 9/1954 Germany ..174/50.57

Related US. Application Data Primary Examiner-John F. Campbell [63] Continuation of Ser. No. 687,672, Dec. 4, 1967, aban- Assismm Examine, Roben w Church doned- AttameyFrank R. Trifari [52] US. Cl ..29/628 R, 29/626 R, 29/522 R,

29/517 R, 72/370 R, 174/152 GM, 174/17.05 R, [57] ABSTRACT 174/17.07 R, 285/3524 R, 287/113 R, 287/205 R, A method ofhermetically sealing a wire, such as a lead-in con- 219/ 150 R ductor for an electrical device, in a metal tube in which the [51] Int. Cl ..H01r 43/00 wire is passed through the tube, a portion of the tube con- Field of Search stricted about the wire, and forcing the wire into one end of the tube which causes the tube to bulge out and the wire thickened beyond the initial diameter of the tube.

2 Claims, 5 Drawing Figures PATENTED rem ma $638305 SHEET 1 UP 2 INVENTOR. KARL HEnvz BOTTCHER BY x W 15% AGE Pmmmnm m2 3.638.305

SHEET 2, 0F 2 INVENTOR. KARL HEINZ BOTTCHER AGENT METHOD FOR FORMING THE VACUUMTIGI-IT CLOSURE OF A THROUGH-CONNECTION This application is a continuation of US. application, Ser. No. 687,672 filed Dec. 4, I967, now abandoned.

The invention relates to a method and a device for the vacuumtight closure of a through-connection formed by a metal wire taken through a metal tube. Such through-connections are frequently used in electric components.

It is known to obtain a vacuumtight seal of such throughconnections by soft or hard soldering. However, solderings have the disadvantage of being expensive and of loading thermally the material in which the through-connection is to be made, usually glass to an extent such that cracks and breakage and hence leakage may occur. If on account of the last-mentioned disadvantage the solderings are made with reduced heat energy, the seals are likely not to be vacuumtight.

It is furthermore known to close through-connections of said kind by compressing or constricting the metal tube. The resultant seal, however, is rarely vacuumtight, since the tube, usually consisting of Ni-Fe, tends to expand resiliently subsequent to compression, whereas the wire, usually consisting of copper, maintains its shape. Owing to the resilient expansion of the tube a fine gap is formed between the tube and the wire so that gas can penetrate.

The invention has for its object to obviate said disadvantages of the known methods of sealing a through-connection formed by a metal wire passed through a metal tube.

The invention is characterized in that the metal tube is constricted and the wire is subsequently forced into the tube so that at the end of the tube the wire is thickened beyond the initial inner diameter of the tube.

The wire is preferably forced into the tube so that the latter is forced to bulge out.

In a further embodiment of the invention the method is carried out by means of a device comprising two pairs of jaws, the first pair narrowing the tube and the second pair gripping the metal wire and pushing it into the tube.

The first pair of jaws has preferably a concave recess between the jaw portion causing the constriction of the tube and the edge of thejaws facing the second pair ofjaws, which recess inhibits the bulging of the tube produced by the forced introduction ofthe wire into the tube.

The invention will now be described more fully with reference to an embodiment shown in the accompanying drawings, in which FIG. I shows a through-connection still to be sealed and formed by a metal wire passed through a metal tube,

FIGS. 2 and 3 show two steps of the method for the vacuumtight seal of the through-connection of FIG. 1,

FIG. 4 shows the vacuumtight through-connection and FIG. 5 shows a detail of the sealing device.

FIG. 1 is a sectional view of a through-connection of the kind frequently employed in electrical assemblies, the interior of which has to be sealed in a vacuumtight manner against the surroundings. The through-connection comprises a partially shown body I, connected with the assembly or the housing thereof and consisting of an insulating material, for example, glass or ceramic material, in which body a tube 2 is fixed by sealing or soldering in a manner not essential to this invention. Through the tube, consisting preferably of a nickel-iron alloy and having, for example, an inner diameter of 1.5 mm., is passed a copper wire having an outer diameter of, for example, 1.2 mm.

The through-connection shown in FIG. I is closed in a vacuumtight manner by narrowing the metal tube 2 and by forcing the wire 3 subsequently into the tube so that at the end of the tube the wire is thickened beyond the initial diameter of the tube.

The two steps of the scaling method, i.e., constriction of the tube and forcing of the wire, as well as the essential parts of the device for carrying out said method are illustrated in FIGS. 2 and 3.

FIG. 2 shows a first pair ofjaws 4, which grips the tube 2,

and a second pair ofjaws 5, which grips the wire 3. The two pairs of aws are provided with recesses of a shape such that the first pair ofjaws 4, when gripping the tube 2. narrows the same to a diameter equal to the diameter of the nondeformed wire 3 or slightly smaller than this. The second pair ofjaws S are provided with recesses gripping the wire so tightly that the wire 3 is taken along and forced into the tube, when in the next step the second pair of jaws 5 is moved downwards against the first jaws 4. The firstjaws 4 are provided with an approximately barrel-shaped recess, which is located above the portion intended for narrowing the tube and the wire and which allows the wire jumped into the tube by the downward movement of the second jaws to bulge out the tube, while the wire is thickened beyond the initial inner diameter of the tube.

The ready seal is shown in FIG. 4 in a sectional view. It will be apparent therefrom that the deformed tube 2, which is more elastic than the wire 3, intimately engages the wire over a comparatively long distance and is substantially cold-welded thereto.

Tests have shown that through-connections thus produced have a higher tightness than 10 Torr l/sec. They permit, in addition, to bend the wire 3 in several directions above the sealing area without adversely affecting the vacuumtightness of the seal. This may be attributed to the fact that in the method according to the invention the forced wire is thickened above the end of the tube and flows intensively together with the tube end.

FIG. 5 shows on an enlarged scale the construction of the first pair ofjaws 4 and a front view and a plan view of the right-hand jaw. From FIG. I and from FIGS. 2 and 3 it will be apparent that the recess has three compartments 6, 7 and 8. The compartment 8 has a diameter substantially equal to the outer diameter of the nondeformed tube 2. The central compartment 7 has a diameter equal to or smaller than the diameter of the nondeformcd wire 3 and narrows the wire and the tube, when the twojaws are joined. The third compartment 6 is substantially barrel-shaped and has a maximum diameter exceeding, preferably by a factor 1.2, the outer diameter of the nondeformed tube 2. It causes the wire 3, forced down, to bulge out the tube as is illustrated in FIGS. 2 to 4.

What we claim is:

I. A method of sealing a metal wire in an open ended metal tube comprising the steps of: passing the wire through the open ended tube until the wire extends beyond the remote end thereof; constricting the tube and causing same to circumferentially bite into and grip the wire by engaging the tube with a first pair ofjaws jointly forming a concave recess opening towards said one end, gripping the wire at a short distance from the one said end of the tube with a second pair ofjaws, and sealing the wire to the tube by axially moving the gripping first and second pairs ofjaws relatively toward each other and forming only the wire between the two pairs of jaws into the tube and causing the tube to bulge outwardly and fill the recess in the first pair ofjaws.

2. A method as claimed in claim I in which the tube consists of nickel-plated nickel-iron and the wire consists of silverplated copper.

23 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 '638,3o5 Dated. Februarv 1. 1972 Inventor) KARL-HEINZ BOTTCHER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Title, change "VACUUMTIGHT" to -VACUUM TIGHT-. After Section [21] insert the following:

. [30] Foreign Application Priority Data Dec. 7, 19 66 Germanup .P l032 Column 1, lines 6, 9, l6, 19, 51, and 66, change "'vacuumtight" to --vacuum tight-m Column 2, lines 12, 41, 43, and 47, change "nondeformed" to --nondeformed-;

line 31, change "vacuumtight" to -vacuum tight.

Signed and sealed this 11th day of July 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting pi'ficen Commissioner of Patents jgggf UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,638,305 Dated, Februarv 1. 1972 In enwfls) KARL-HEINZ BO'I'TCHER It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Title, change "VACUUMTIGHT" to --VACUUM TIGH'1'.

After Section [21] insert the f llow. ng:

[30] Foreign Application Priority Data Dec. 17, 1966 German. .P41032 Column 1, lines 6, 9 16, 19, 51, and 566, change "vacu'umtight" to vacuum tight-.

Column 2, lines 12, 41, 43, and 47, change nondeformed" to -nondeformed;

line 31, change "vacuumtight" to -vacuum tight-.

Signed and sealed this 11th day of July 1972.

(SEAL) Attest:

EDWARD DLFLETCHER, JR. ROBERT GOT TSCHALK Attesting pfiicpn Commissioner of Patents 

1. A method of sealing a metal wire in an open ended metal tube comprising the steps of: passing the wire through the open ended tube until the wire extends beyond the remote end thereof; constricting the tube and causing same to circumferentially bite into and grip the wire by engaging the tube with a first pair of jaws jointly forming a concave recess opening towards said one end, gripping the wire at a short distance from the onE said end of the tube with a second pair of jaws, and sealing the wire to the tube by axially moving the gripping first and second pairs of jaws relatively toward each other and forming only the wire between the two pairs of jaws into the tube and causing the tube to bulge outwardly and fill the recess in the first pair of jaws.
 2. A method as claimed in claim 1 in which the tube consists of nickel-plated nickel-iron and the wire consists of silver-plated copper. 